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Nodal Peripheral T-cell Lymphomas

Three clinically important subtypes of nodal peripheral T-cell lymphoma are currently recognised.

• Common Type
• Angio-immunoblastic Type
• Anaplastic Large Cell Lymphoma

Common Type

Presentation

• These usually present with lymphadenopathy with or without systemic symptoms similar to Diffuse Large B-cell Lymphoma (DLBCL).
• Advanced stage disease and extranodal involvement may be more common than DLBCL.

Diagnosis

• There is infiltration and replacement of the normal nodal or other tissue
• The tumour cell morphology is highly variable but most cases have a mixture of medium and large lymphoid cells showing highly irregular nuclei
• The phenotype is typically:
  • CD3⁺, CD2⁺, CD5⁺, CD4⁺, CD45RO⁺ but there is variation between cases
• large number of reactive cells including macrophages, eosinophils and plasma cells may be present in some cases.

Treatment and Outcome

• Most patients are treated initially with CHOP or similar type combination chemotherapy.
• The overall outcome is poor reflecting presentation with advanced stage disease and more aggressive behaviour of T-cell lymphomas. A small group of patients has a more indolent course.

Angio-immunoblastic Type

Diagnosis

• neoplastic cells which are medium sized T-cells, usually with a small proportion of larger blast cell. These are CD4⁺ peripheral T-cells and may have an abnormal phenotype. A small number of cells may contain Epstein-Barr virus, the significance of this is uncertain.
• Proliferating vessels, follicular dendritic cells, macrophages and polyclonal reactive plasma cells.

• fever and raised plasma viscosity
• skin rashes
• hypergammaglobulinaemia often with a positive Coomb's test
• haemolysis and less commonly immune thrombocytopenia

CD23 immunoperoxidase stain of lymph node section.	Lymph node section - H&E stained

Outcome and Treatment

• The outcome is poor with a median survival of less than 2 years.
• There is no consensus treatment. Most patients will be initially managed with a CHOP type combination chemotherapy.

Anaplastic Large Cell Lymphoma

Presentation

• Present with nodal or extranodal masses.
• Systemic symptoms may be present in some patient with extensive disease.

Diagnosis

• In typical cases the cells are very large with abundant cytoplasm, often with a distinctive golgi, large nuclei with prominent nucleoli. Multi-lobated cells are frequent. A number of morphological variants are described.
• The cells are strongly CD30⁺ and CD45⁺ and have variable expression of pan-T-cell markers.
• The t(2;5) is a key diagnostic feature of anaplastic large cell lymphoma. This results in a fusion protein NPM-ALK which has abnormal kinase activity.
• The t(2;5) is found in younger patients and tumours with this translocation have a much better outcome.
• It is essential to differentiate this tumour from CD30⁺ cutaneous large cell lymphoma. This is complicated by the relatively frequent involvement of the skin in systemic anaplastic large cell lymphoma.

Treatment and Outcome

• Initial treatment is usually with CHOP type combination chemotherapy.
• This is critically dependant on the t(2;5). Tumour with the translocation have >70% 5 year survival. Those without the t(2;5) have a 25% 5 year survival. This effect suggests that the t(2;5) tumours should be regarded as a separate entity.
• The outcome also depends on the International Prognostic Index

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